1. Field of the Invention
The present invention relates to temperature sensors capable of detecting a temperature of a detection target, for example, an exhaust gas flowing in an exhaust gas pipe placed in an exhaust gas purifying system of an internal combustion engine such as a diesel engine.
2. Description of the Related Art
A temperature sensor detects a temperature of an exhaust gas emitted from an internal combustion engine mounted to a motor vehicle. Such a temperature sensor is comprised of a sensor part and a wire harness. Through the wire harness, the temperature sensor outputs a detection signal to a control device mounted to the motor vehicle.
For example, a temperature sensor disclosed in a Japanese patent laid open publication No. 2002-221451 is comprised of a sensor part, core wires of a sheath pin, a connector, and a protection tube. The sensor part is capable of detecting a temperature of a detection target. The core wires of the sheath pin are connected to the sensor part. Through the connector the core wires of the sheath pin and lead wires are connected. The protection tube accommodates the core wires of the sheath pin. The connector and the connection part between the core wires of the sheath pin and the lead wires are fixed by ceramic material. The inside of the protection tube is filled with the ceramic material as a mold part. The lead wires are inserted into holes which are formed in the protection tube and supported by a corresponding bush therein. In addition, a cylindrical metal spacer is placed in an axial direction of the sheath pin between the bush and a stopper made of ceramic material.
However, the conventional temperature sensor having the above structure requires the mold part made of ceramic material, the bush, the spacer, etc. in order for the part, with which the core wires of the sheath pin and the corresponding lead wires are electrically connected together, such as ease of assembly, electrical insulation, to have necessary functions such as an electrical conductivity, a physical strength, a heat resistance of sealing, etc. Specifically, such a stopper is used in the temperature sensor in order to keep various functions such as ease of assembly, electrical insulation and conductivity between the core wires of the sheath pin and the lead wires. Further, the spacer is placed between the stoppers and the bushes in order to stop the stoppers to move in an axial direction and to keep the tension function thereof. Still further, the stoppers are caulked in order to keep the heat resistance function of sealing.
Accordingly, the above conventional temperature sensor has a complicated structure in order to keep the necessary functions previously described. The structure of the conventional temperature sensor prevents the manufacturing process of producing the temperature sensor form being complicated and the manufacturing cost thereof from being decreased.